<template>
  <div class="spec-preview">
    <img :src="skuUrl.imgUrl" />
    <div class="event"
    ref="event"
    @mousemove="handleMove"
    ></div>
    <div class="big">
      <img :src="skuUrl.imgUrl" ref="big"/>
    </div>
    <!-- 遮板 -->
    <div class="mask" ref="mask"></div>
  </div>
</template>

<script>
  export default {
    name: "Zoom",
    data(){
        return{
          lightIndex:0
        }
    },
    props:{
      skuImageList:{
        type:Array,
        default:()=>[]
      }
    },
    computed:{
       skuUrl(){
         return this.skuImageList[this.lightIndex] || {}
       }
    },
    mounted(){
      this.$bus.$on('prcIndex',(index)=>{
          this.lightIndex = index
      })
    },
    methods:{
      handleMove(e){
          let ma = this.$refs.mask
          let ev = this.$refs.event
          let big = this.$refs.big

          let x = e.offsetX - ma.offsetWidth/2
          let y = e.offsetY - ma.offsetHeight/2

          let w = ev.offsetWidth - ma.offsetWidth
          // x 边界判定
           if(x <= 0)x = 0
           if(x >= w)x = w
          
          // y 边界判定
          if(y <= 0) y = 0
          if(y >= w) y = w
          
          // 小图
          ma.style.left = x + 'px'
          ma.style.top = y + 'px'
          // 大图
          big.style.left =-2 * x + 'px'
          big.style.top = -2 * y + 'px'
      }
    }
  }
</script>

<style lang="less">
  .spec-preview {
    position: relative;
    width: 400px;
    height: 400px;
    border: 1px solid #ccc;

    img {
      width: 100%;
      height: 100%;
    }

    .event {
      width: 100%;
      height: 100%;
      position: absolute;
      top: 0;
      left: 0;
      z-index: 998;
    }

    .mask {
      width: 50%;
      height: 50%;
      background-color: rgba(0, 255, 0, 0.3);
      position: absolute;
      left: 0;
      top: 0;
      display: none;
    }

    .big {
      width: 100%;
      height: 100%;
      position: absolute;
      top: -1px;
      left: 100%;
      border: 1px solid #aaa;
      overflow: hidden;
      z-index: 998;
      display: none;
      background: white;

      img {
        width: 200%;
        max-width: 200%;
        height: 200%;
        position: absolute;
        left: 0;
        top: 0;
      }
    }
    
    .event:hover~.mask{
      display:block;
    }
    
    .event:hover~.big {
      display: block;
    }
  }
</style>